It is well known to provide a refrigeration system for use with one or more temperature controlled storage devices such as a refrigerator, freezer, refrigerated merchandiser, display case, etc. that may be used in commercial, institutional, and residential applications for storing or displaying refrigerated or frozen objects. For example, it is known to provide a refrigeration system having a refrigerant for direct expansion in a single loop operation to provide cooling to heat exchanger such as an evaporator or chiller. It is also known to provide a connection point for readily attaching refrigerant charging equipment and/or pressure testing equipment to charge or pressure test the piping and other components of the system. However, such known connection points tend to leak over time and result in loss of refrigerant from the system and the need for expensive re-charging and pressure testing activities. A positive shutoff device for use with a charging and testing connection point for both new and existing refrigeration systems is provided.